Alpha Draconis is the Bayer designation of the star traditionally called Thuban. It lies in the northern constellation Draco, about 270 light-years away. [1][2]
The name refers to a star, so this page is about the astronomical object rather than another topic with similar wording. That distinction is useful when you encounter “Alpha Draconis” in a search or discussion: the surrounding context can tell you whether someone means the star or something else. This overview identifies the name and its basic astronomical context; later sections cover what makes the star notable and how to tell it apart from similar names.
As a practical cue, a reference that pairs Alpha Draconis with the constellation Draco is discussing the star. If the name appears without that context, check the surrounding wording before assuming it has an astronomical meaning. That simple check keeps the name clear without confusing a star’s designation with an unrelated use of similar words.
Why is it also called Thuban?
Thuban is the traditional name of Alpha Draconis, while “Alpha Draconis” is the Latinized form of its Bayer designation. [2] The star is in the constellation Draco, about 270 light-years away. [1]
Why the names differ
The star’s Bayer designation is α Draconis, which is written in Latin letters as Alpha Draconis.[2] “Thuban” is its traditional name; “Alpha Draconis” renders the Greek-letter designation α Draconis in Latin letters. [2]
For example, a star chart might label it “α Dra,” while an astronomy article spells out “Alpha Draconis” or uses “Thuban.” Those labels point to the same star, so you can read them as alternate names rather than separate objects. [2]
Finding it in the sky
To place Thuban, look for Draco, the northern constellation that contains it. The star is about 270 light-years from Earth, so it is a distant point of light rather than a nearby object. [1]
The wording also gives you a useful clue when reading about it: “Alpha Draconis” combines the Greek letter alpha with Draco’s name. That makes the formal designation easier to recognize when you encounter it alongside the familiar name Thuban. [2]
When you compare a star chart with an astronomy article, check both the constellation label and the star’s name. If one calls it Thuban and another calls it Alpha Draconis, they are referring to the same star in Draco. [1][2]
What makes Alpha Draconis notable?
Alpha Draconis is notable because it belongs to a pair of stars that eclipse one another as they orbit. The pair completes an orbit every 51.4 days, so the eclipses recur on that cycle. [3]
When one star passes in front of the other from our viewpoint, it blocks some of the other star’s light. As the stars continue around their orbit, the pattern repeats; the companion is therefore part of what makes Alpha Draconis an eclipsing system. [3]
That regular cycle gives astronomers a recurring change in brightness to observe. Rather than a one-time event, the eclipses happen as the stars repeatedly move into alignment from our perspective. [3]
For a simple way to picture it, imagine two lamps going around each other: when one crosses in front of the other, the combined light dims, then brightens again as they separate. The stars’ 51.4-day orbit sets the pace of that recurring pattern. [3]
This is what makes the system stand out: its companion’s motion produces predictable eclipses, rather than Alpha Draconis appearing as a single, unchanging point of light. [1]
How can you tell the star from similar names?
Read the surrounding context
When you see Alpha Draconis or Thuban alongside terms such as Draco, stellar eclipses, or TESS, the name points to the star discussed here. NASA identifies Alpha Draconis as Thuban and places it in the constellation Draco; its report also discusses TESS observations of the star’s eclipses. [1] [3]
That context helps separate an astronomy reference from an unrelated use of similar wording. For example, a sentence about TESS observing eclipses is about a star system, while a bare mention of “Alpha Draconis” without astronomy terms may need more context before you can tell what the writer means.
Check for astronomy clues
Look for nearby words that describe objects or observations in space. “Draco” is a strong clue because it appears in NASA’s identification of Alpha Draconis, while “stellar eclipses” and “TESS” point to the star’s observed astronomical behavior. [1] [3]
A useful reading habit is to check the whole sentence rather than matching the name alone. If a passage connects Thuban with Draco or describes TESS detecting eclipses, it is discussing the astronomical star; if it uses similar wording in another subject, do not assume it refers to Thuban.
Avoid name-only assumptions
Similar wording by itself is not enough to identify a subject. When you are reading a search result, caption, or discussion thread, use the surrounding terms—such as Draco, stellar eclipses, or TESS—to decide whether Alpha Draconis means the star.
For instance, “Alpha Draconis and its companion eclipse each other” clearly signals an astronomy context, while an isolated label does not tell you what topic it belongs to. The safest approach is to confirm that the nearby text names a constellation, a star, an observation, or another space-related detail before treating the reference as astronomical.
The quick answer
Remember that Alpha Draconis is Thuban, and its eclipsing stellar companion is the feature that sets the system apart. If you encounter the name again, keep those two details together: they identify the star and the distinctive behavior of its companion system. [1][3]
For a quick check, look for the astronomy context: a mention of Draco or stars eclipsing one another points to the subject discussed here. Then use the companion’s eclipses as the identifying detail, rather than treating Alpha Draconis as only a name to memorize. [1][3]
If you want to learn more, look for an astronomy explanation of Thuban and its stellar companion. That will keep your next step focused on the star and the feature that makes it memorable, without confusing it with other uses of similar wording.
Sources
The star’s Bayer designation is α Draconis, which is written in Latin letters as Alpha Draconis.[2]